The invention generally relates to the fabrication of semiconductor devices and associated thermoelectric cooling elements.
Heat transfer devices, such as thermoelectric coolers (TECs), are used in some high speed semiconductor devices, such as optoelectric semiconductor devices. TECs incorporate discrete elements which are electrically coupled together. These elements are generally formed from fragile materials commonly used in semiconductor fabrication, such as bismuth telluride.
Known methods of electrically coupling the elements to each other include aligning the elements with each other and soldering individual TEC elements in a matrix to a metallized support structure, such as a submount formed of beryllium oxide.
For example, a conventionally fabricated semiconductor device 10, as shown in FIG. 1, includes an optoelectronic device 12 physically situated on and electrically coupled to a thermoelectric cooling (TEC) device 25. The TEC device 25 includes a metallized ceramic plate 14, a plurality of fragile TEC elements 18, and a heat sink 20. Each of the elements 18 is positively-doped at one end and negatively-doped at the opposite end. The elements 18 are electrically coupled to each other through soldered connections 23. The elements 18 are further electrically coupled to the plate 14 and the heat sink 20 via solder balls 22.
The known methods of electrically connecting conventional TEC devices 25, i.e., soldering connections, to semiconductor devices present a disadvantage in that tolerances in the Z-axis direction (FIG. 1) of the semiconductor devices are large, generally no smaller than one mil, or one times ten to the minus three (1xc3x9710xe2x88x923) of an inch. Further, the standard deviation between semiconductor devices so manufactured is also large, often resulting in large numbers of a batch of such semiconductor devices failing to meet production standards.
In one aspect, the invention provides an apparatus with a heat transfer structure that includes a plurality of heat transfer elements each having a positively-doped region and a negatively-doped region, an encapsulating material encapsulating the heat transfer elements in a block, and conductive connectors formed on the encapsulating material and electrically connecting the heat transfer elements together. The apparatus further includes an optoelectronic device electrically connected to the heat transfer structure.
In another aspect, the invention further provides a thermoelectric cooling device including a plurality of heat transfer elements each having a positively-doped region and a negatively-doped region, an encapsulating material encapsulating the heat transfer elements in a block, and conductive connectors electrically connecting the heat transfer elements together, the conductive connectors being formed on the encapsulating material.
In another aspect, the invention also provides a method for fabricating a semiconductor device. The method includes encapsulating a plurality of heat transfer elements within an encapsulating material to form a block of encapsulated heat transfer elements, each element having a positively-doped and a negatively-doped region, providing at least one resist layer covering an end of the heat transfer elements, selectively preparing locations in the resist layer, each of the locations extending to the encapsulating material and between one heat transfer element and an adjacent heat transfer element, and forming conductive material in the locations, wherein the conductive material electrically connects the heat transfer elements together.
These and other advantages and features of the invention will be more readily understood from the following detailed description of the invention which is provided in connection with the accompanying drawings.